Use Case 04 - Create New Object

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Goal

Create new content on a Member Node.

Summary

A user adds new content to a Member Node (MN). The operation of adding new content to a Member Node is atomic to the Member Node, meaning there is no dependency on the replication or synchronization processes for the successful completion of a create operation.

The metadata is retrieved by the CN using a pull mechanism (CN requests content from the MN) which may be triggered by a timer event or notification from the MN.

The availability of new content on a MN is indicated by a flag in the response to a ping() message issued by a CN. The CN then retrieves a list of changes from the MN and for each change, retrieves the experiment metadata, stores it and generates a search metadata document by extracting content from the experiment metadata. The changes to the CN (stored experiment metadata, update search metadata) are replicated to the other CNs (Use Case ###). The CN schedules replication of the data package across other MNs (Use Case 06).

Actors

Member Node, additional Member Nodes, Coordinating Nodes

Preconditions

• Use is authenticated and so client application has an auth_token for the process.
• DataONE system operational
• MN is registered and is monitored

Triggers

• New data package is present on Member Node
• An existing data package is modified on a Member Node
• A data package is deleted from a Member Node

Post Conditions

• New data package is replicated across MNs
• Search metadata is updated
• Operation recorded in logs
• CN update of search metadata
• CN replication of metadata
• Watchers notified of change

Notes

• Are IDs are pegged to versions? If so, update might differ more radically from create.
• If delete is a metadata operation only, then will be very similar to update. But if it is a physical operation, it becomes more complex. Will there be an archival copy? Will member nodes that hold replicas be “forced” to destroy the replicas?
• Is submit from a member node a push or pull?
• Should queuing of a submission within a member node be required for success? (We assume yes, to guarantee replication of submissions).
• Can data packages be deleted or modified?

Figure 1. Use case 04.

Figure 2. Create, update, delete, science metadata or data object in Member Node.